1. Field of the Invention
The present invention relates to a method and system of enhancing accelerator pedal safety interlock systems that utilize an input to determine the status of the vehicle condition and the corresponding accelerator pedal safety interlock. Typically, accelerator pedal safety interlock systems use a discrete input which don't allow for circuit continuity checks (e.g. input is either open or closed and cannot detect a short circuit to either power or ground, or an open circuit). Although circuit continuity failure may be unable to be measured electrically, a fault may be determined based on a rationality check. If it is determined that the input is illogical (e.g. accelerator pedal interlock requests the accelerator pedal be inhibited at a high rate of vehicle speed the illogical request to inhibit the vehicle accelerator pedal request may be ignored, allowing continued operation of the vehicle. If an illogical request to inhibit the accelerator pedal is received at a high rate of vehicle speed, the accelerator pedal inhibit should be disabled until the switch is disabled until the switch is validated. A calibratible torque derate option should be provided to optionally reduce the amount of available engine torque in the event that a fault is detected. Limiting the engine torque will limit the overall operation of the vehicle but will still permit the vehicle to operate until the fault condition can be diagnosed.
2. Description of the Related Art
Hawkins et al., U.S. Pat. No. 6,814,053 discloses an engine control system for compression ignition engines that employ a microprocessor-based controller to detect engine operation in a speed range previously determined to be undesirable, and responding to the detection by changing the operation of the engine. In the preferred embodiment, the controller commands a parameter for adjusting engine operation to each a different speed outside of first and second thresholds defining the undesirable range in a time period subsequent to the detection.
McKenzie et al., U.S. Pat. No. 6,640,469 discloses a vehicle and a device for limiting the speed operation of the vehicle if the engine is overloaded.
Hawkins et al., U.S. Pat. No. 6,371,081 discloses an engine controller capable of operating in both a torque governing mode and a speed governing mode simultaneously, and a method of operation whereby speed governing may be enabled and disabled while simultaneously providing a valid speed request signal to the controller. The speed governor signal has an enabled state and a disabled state and is generated external to the controller and monitored by the speed governor. The speed request signal is simultaneously monitored by the speed governor. The speed governor is operative to control the speed of the engine proportional to the speed request signal while the speed governor signal is in the enabled state. The speed governor is disabled by the setting the speed governor signal into the disabled state. A torque governor may also be operational within the controller. The torque governor monitors a torque request signal that it uses to control a torque generated by the engine.